Seattle-Tacoma International ⇄ Washington Dulles International SEA–IAD
Airlines flew 3,675 flights between Seattle-Tacoma International SEA in Seattle, WA and Washington Dulles International IAD in Washington, DC in the twelve months to July 2026, both directions together: 526,502 passengers in 611,757 seats, 86% of them filled, and 689,811 pounds of freight. 2,305 miles, about 263 minutes in the air, on 3 airlines: Alaska Airlines Inc. (1,661), United Air Lines Inc. (1,300), Delta Air Lines Inc. (714). Planning to fly it yourself? The weather and winds along this route right now.
Flights by month both directions
By month, as a table
| flights | |
|---|---|
| 1/25 | 205 |
| 2/25 | 185 |
| 3/25 | 233 |
| 4/25 | 310 |
| 5/25 | 406 |
| 6/25 | 471 |
| 7/25 | 485 |
| 8/25 | 442 |
| 9/25 | 358 |
| 10/25 | 307 |
| 11/25 | 234 |
| 12/25 | 249 |
| 1/26 | 199 |
| 2/26 | 186 |
| 3/26 | 229 |
| 4/26 | 255 |
| 5/26 | 403 |
| 6/26 | 392 |
| 7/26 | 421 |
Passengers by month
By month, as a table
| passengers | |
|---|---|
| 1/25 | 27,263 |
| 2/25 | 24,380 |
| 3/25 | 31,078 |
| 4/25 | 42,990 |
| 5/25 | 58,279 |
| 6/25 | 70,105 |
| 7/25 | 75,213 |
| 8/25 | 68,434 |
| 9/25 | 48,442 |
| 10/25 | 40,228 |
| 11/25 | 29,724 |
| 12/25 | 35,376 |
| 1/26 | 25,424 |
| 2/26 | 23,870 |
| 3/26 | 33,525 |
| 4/26 | 37,033 |
| 5/26 | 57,716 |
| 6/26 | 60,211 |
| 7/26 | 66,519 |
The airlines twelve months, both directions
| Airline | Flights | Passengers | Seats filled | Service |
|---|---|---|---|---|
| Alaska Airlines Inc. AS | 1,661 | 252,624 | 86% | scheduled passenger service |
| United Air Lines Inc. UA | 1,300 | 201,668 | 89% | scheduled passenger service |
| Delta Air Lines Inc. DL | 714 | 72,210 | 78% | charter passenger service, scheduled passenger service |
The aircraft as the airlines report their types
| Aircraft | Flights | Seats a flight | Passengers |
|---|---|---|---|
| Boeing B737 Max 900 | 1,277 | 178 | 199,785 |
| Boeing 737-900ER | 1,065 | 178 | 163,823 |
| A220-300 BD-500-1A11 | 704 | 130 | 71,512 |
| Boeing B737 Max 800 | 333 | 166 | 49,537 |
| Boeing 737-800 | 273 | 164 | 39,662 |
| A200-100 BD-500-1A10 | 7 | 109 | 574 |
| Boeing 737-700/700LR/Max 7 | 6 | 126 | 703 |
| Airbus Industrie A319 | 6 | 126 | 645 |
| Boeing 757-200 | 3 | 72 | 124 |
| Airbus Industrie A320-100/200 | 1 | 150 | 137 |
SEA → IAD this direction alone · flown January 2025 to July 2026
1,843 flights of 1,864 scheduled, 263,954 passengers in 306,326 seats, 504,102 pounds of freight, 29,919 pounds of mail. Alaska Airlines Inc. 835; United Air Lines Inc. 650; Delta Air Lines Inc. 358.
IAD → SEA this direction alone · flown January 2025 to July 2026
1,832 flights of 1,864 scheduled, 262,548 passengers in 305,431 seats, 185,709 pounds of freight, 1,735 pounds of mail. Alaska Airlines Inc. 826; United Air Lines Inc. 650; Delta Air Lines Inc. 356.
Source: the Bureau of Transportation Statistics' T-100 Segment table (all carriers). A flight is one departure performed on this segment; seats and passengers are the airlines' own monthly reports; "seats filled" is passengers divided by seats. The miles are the DOT's great-circle distance. Both ends: Seattle-Tacoma International SEA and Washington Dulles International IAD; all routes.